Storage media such as hard disk drives (hereinafter abbreviated as “HDDs”) store data in units called sectors. When the size of data to be written on a storage medium is smaller than the sector size, the data is stored in one sector. Even when there is an empty area in the sector, other information is not stored in the empty area. When the size of data to be written on the storage medium is greater than the sector size, the data is stored across a plurality of sectors.
Different types of storage media have different sector sizes. The sector size of most HDDs has been 512 bytes (hereinafter abbreviated as “512 B”) for many years. HDDs with a sector size of 4 kilobytes (hereinafter abbreviated as 4 KB) have come into widespread use in recent years. 4 KB is 4096 B, which is eight times the 512 B.
Hereinafter, a storage medium having a sector size of 512 B is referred to as a “512-B-sector storage medium”. A recording medium having a sector size of 4 KB is referred to as a “4-KB-sector storage medium”. A “512-B-sector storage medium” is rephrased by a “storage medium based on 512 B sectors”. A “4-KB-sector storage medium” is rephrased by a “storage medium based on 4 KB sectors”. Examples of storage media include HDDs, SSDs (Solid State Drives), flash memories, and floppy disks (“floppy” is a registered trademark).
Note that a storage medium with a sector size slightly greater than 512 B (for example, 520 B or 528 B) will also be referred to as a “512-B-sector storage medium” hereinafter for convenience of explanation. Such a storage medium generally includes reserved extra area storing sector check codes and other information in addition to 512 B area. The check code is ECC (Error Checking and Correction), for example. Similarly, a storage medium with a sector size slightly greater than 4096 B (for example, 4104 B, 4160 B, or 4224 B) will also be referred to as a “4-KB-sector storage medium” hereinafter for convenience of explanation. The size of 4160 B is eight times the 520 B.
One of the reasons why 4-KB-sector storage media has come into widespread use will be described. The ratio of the number of bytes required for ECC to the storage capacity of a 4-KB-sector storage medium is smaller compared to that of a 512-B-sector storage medium. Accordingly, the storage capacity is more efficiently used on a 4-KB-sector storage medium than on a 512-B-sector storage medium. This is one of the reasons why 4-KB-sector storage media are widely used.
As for hosts, which are information processing devices that access storage media, more and more OSs (Operating Systems), which cause the hosts to operate, are starting to support 4-KB-sector storage media. However, there are still many hosts that run old OSs that do not support 4-KB-sector storage media.
A host that supports 4 KB sectors will be hereinafter referred to as a “4-KB-sector host”. A host that does not support 4 KB sectors (i.e., a host that supports conventional 512 B sectors) will be hereinafter referred to as a “512-B-sector host”. A “4-KB-sector host” is rephrased by a “host based on 4 KB sectors”. A “512-B-sector host” is rephrased by a “host based on 512 B sectors”.
Thus, there may be situations where 512-B-sector storage media, 4-KB-sector storage media, 512-B-sector hosts, and 4-KB-sector hosts are mixedly used.